I pre-purchased GW2 a while ago and this weekend will be the first beta event I will be participating in.
The interesting thing is that the whole game consists of only two files. A compressed gw2.dat file that contains all game assets, currently sitting at 15.3 GB. And gw2.exe, the launcher that downloads updates and launches the game. There are two additional files created when the launcher is ran, chrome.log and Gw2.tmp. Both are usually empty.
The interesting thing is how GW2 uses single humongous file for assets. Seems to work very well for them. Since this beta is not under NDA, I'll be reporting my impressions on the beta weekend later.